package io.github.novaframe.common.util;

import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * 
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.
 * 
 * @author Locki
 * @date 2014年12月29日
 *
 */
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {
	
	private final static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);
	
	private static ApplicationContext ac = null;

	/**
	 * 取得存储在静态变量中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		assertContextInjected();
		return ac;
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) ac.getBean(name);
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return ac.getBean(requiredType);
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext为Null.
	 */
	public static void clearHolder() {
		logger.debug("Clean SpringContextHolder ApplicationContext:" + ac);
		ac = null;
	}

	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中.
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) {

		if (SpringContextHolder.ac != null) {
			logger.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.ac);
		}

		SpringContextHolder.ac = applicationContext; // NOSONAR
	}

	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量.
	 */
	@Override
	public void destroy() throws Exception {
		SpringContextHolder.clearHolder();
	}

	/**
	 * 检查ApplicationContext不为空.
	 */
	private static void assertContextInjected() {
		Validate.validState(ac != null, "applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");
	}

}
